TUESDAY, Jan. 5, 2016 (HealthDay News) -- Lifestyle changes that include a healthy diet and regular exercise appear to improve heart function and exercise capacity in people with a particular form of heart failure, a new study reports.

Heart failure with preserved ejection fraction (HFPEF) is a form of heart failure that's on the rise. It most often affects overweight and obese older women. This type of heart failure leads to fatigue and shortness of breath during activities, which can affect the ability to exercise, according to the study authors.

The study included 100 obese older people with HFPEF. The randomized clinical trial was funded by the U.S. National Institutes of Health.

Researchers from Wake Forest University School of Medicine led by Dr. Dalane Kitzman divided the participants into four groups: diet alone, exercise alone, both diet and exercise, and a control group who didn't get any treatment.

After 20 weeks, assessments of the patients' peak exercise oxygen consumption revealed that those in all three treatment groups saw improvements in their ability to exercise. The patients treated with both diet and exercise however, had nearly twice the improvement in their oxygen consumption, the study showed.

In addition to boosting their tolerance for exercise, the study also revealed that diet and exercise reduced the amount of fat cells within the leg muscles, which can improve heart failure patients' exercise capacity.

More research is needed to investigate the effects of diet on muscle mass, the study's authors said, but their findings support a treatment approach for heart failure that includes diet and exercise.

The results were published online Jan. 5 in the Journal of the American Medical Association.